Turbocharger - Basics Principle
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Transcript of Turbocharger - Basics Principle
The basic principle of an exhaust gas turbocharger
Increasing air density
The exhaust gas turbocharger fitted with a by-pass
A turbocharger has two sets of problems:
• The turbine speed at the top end of the speed range is high and the air is
compressed more than is necessary.
• At the bottom end of the speed range, the exhaust gas turbine does not reach the
required speed. The air is not compressed sufficiently and the engine is unable to deliver the desired power output (turbo
lag).
It was decided to make a compromise regarding the design of the exhaust gas
turbocharger fitted with a by-pass.
Turbo charger with by-pass
Intake manifold pressure
Disatvantages:
ECU is not able to influence the pressure
Turbo lag
The adjustable Turbocharger
Advantages:
nearly no Turbo lag
produces the necessary
compression not only at the top end of the speed range but also across the full speed range
Function
Ordinary pipe
Same (low) pressure everywhere
Narrowed pipehigh
pressure
High speed
Venturi effect
Low engine speed and high charge pressure are required
Since the exhaust gas is forced to pass through the restricted cross-section more quickly, the turbine
wheel rotates faster.The high turbine speed at low engine speed generates the required charge
pressure
High engine speed
In contrast to the by-pass, the entire exhaust gas flow can be fed through the
turbine in this way
The vanes free a larger inlet cross-section, thereby ensuring that the
required charge pressure is not exceeded.
Adjusting the vanes
Vacuum control for flat vane angle adjustment
This vane position allows the fastest possible maximum charge pressure build-up.
The engine control unit controls the solenoid valve for vacuum supply.
The maximum vacuum can, as a result, act on the low-pressure box.
VacuumAtmosphere
Pulse wide of signal
About 80%
Vacuum control for steep vane angle adjustment
VacuumAtmosphere
Atmospheric pressure is fed into the low pressure box.
The vanes are adjusted at a steep angle.
This position is also the adjustment used in emergency operation.
Pulse wide of signal
About 20%
Vacuum control for intermediate stages of vane adjustment
More or less power must be available to the engine to cater for momentary driving conditions. Therefore, the turbocharger must deliver the optimum charge pressure.
Pulse wide of signal
Changing between 20 and 80%
System overview
System Components
Wiring diagram
Another Type of adjustable Turbo charger